Multi-ply bags

ABSTRACT

This disclosure relates to improvements in multi-ply bags which generally include at least an outer wrapper and an inner liner, and is particularly directed to a bottom construction formed by adhesively securing together a plurality of closure panels or flaps. The securement is effected by forming heat-shrunk openings in the inner liner to expose the interior of the outer wrapper which is brought into overlying adhesive contact with the exterior of another closure flap or panel such that the bond is between the material of the outer wrapper.

United States Patent Inventor Vernon Martin Charlotte, N.C. Appl. No.856,448 Filed Sept. 9. 1969 Patented Aug. 3, 1971 Assignee ContinentalCan Company, Inc.

New York, N.Y.

MULTI-PLY BAGS 5 Claims, 4 Drawing Figs.

US. Cl 229/55, 229/57 Int. CL. 365d 33/02 Field Search 229/53, 55, 5 8,59, 57

[56] References Cited UNITED STATES PATENTS 2,864,549 12/1958 Hayward etal 229/57 3,325,082 6/1967 Naylor 229/55 3,133,387 5/1964 Harrison215/38 A Primary Examiner-David M. Bockenek Anamey-Diller, Brown, Ramik& Holt ABSTRACT: This disclosure relates to improvements in multi-plybags which generally include at least an outer wrapper and an innerliner, and is particularly directed to a bottom construction formed byadhesively securing together a plurality of closure panels or flaps. Thesecurement is effected by forming heat-shrunk openings in the innerliner to expose the interior of the outer wrapper which is brought intooverlying adhesive contact with the exterior of another closure flap orpanel such that the bond is between the material of the outer wrapper.

MULTl-PLY BAGS The most simple conventionally fabricated multi-ply bagis a two-ply construction having an.inner liner. and an outer wrapper.Such a bag is customarily fabricated from two separate but continuous.webs which are laminated, spot pasted, or otherwise secured to eachother. In bags of this type it is known to form the liner webfrom-grease resistant, moistureproof material while the web forming thewrapper is generally constructed from heavy gauge paper stock materialto provide the requisite bagstrengthrOne such conventional bag isdisclosed in commonly ,assigned US. Pat. No. 3,289,915, issued Dec. 6,1966, in the name of Anthony];

Civitello.

Inthe latter-noted patent, reference is made to the difficultyin formingcommercially acceptable bag bottoms'because of the difficulty ofadhesively securing-the inner liner of one flap or closure to an outersurface of the wrapper and another flap or closure to form the finalclosure. of the bag bottom. This is because the inner liner is eitherconstructed from or coated with polyethylene or. other relativelyimpermeable material,

and the water of conventionallyemployed water-based adhe sives is notabsorbed by the liner thus precluding the formation of a strong sealbetween-the liner and that portion of the wrapper to which the linerflap overlaid. In'addition, the im--- penneable and generallynonwettable nature of such liners or coatings thereon results inexcessive setting up time, thereby increasing the cost for themanufacture of such bags.

One solution to this problem is provided in the latter-noted patent.bysevering a portion of the liner ofanouter closure" flap and folding thesevered portion .upon itself to expose the inner surface of the outerwrapper of the outer closure flap to. an outersurface of an adjacentinner closureflap whereupon drawn from separate rolls such that'the'linerweb may be severed and the portion folded prior to thewebs-beinglaminated to each other.

I In keeping with the present invention a multi-ply bag is constructedfrom either two separate. webs each drawn from a separate roll, or asingle laminated web drawn from a single roll. In either case the webwhich eventually forms the inner liner is constructed fromheat-shrinkable synthetic polymeric I or copolymeric material, such aspolyoletin, polyethylene, polypropylene, pliofilm, etc. The-. linermaterial maybe nonoriented or oriented, although in the practiceof theinvention oriented materialhas been found more desirable. During thefeeding of the individual or laminated webs heating means of any typeare applied directly against'or close to portions of the inner web whicheventually form the inner surface of the outennost closure panel or flapsuch that the heat causes ther mal degradation of theliner materialresulting in its shrinking to form one or more openings. This may beaccomplished by, for example, positioning any type of conventionalheating elements upon a rockable shaft disposed transverse to the pathof movement of the liner web. The shaft may then be rocked in timedrelationship to the movement of the liner web, by means such asdisclosed in the latter-notedpatent, to bring the heating elementscontiguous to or in directcontact with the liner '65 material whereupontheheat thermally degrades the inner linertube at one or more points inthe eventual .outerrnost clov sure, flap area to form the openingsheretofore noted whereuponadhesive thereafter applied to the websresults'in the bonding of the inner surface of the outermost closure.flap of thewrapper to adjacent exterior surfaces of the wrappermaterial.

It is, therefore, a primary object of. this invention to provideanimproved .multi-ply bag formedof separate or laminated liner and.wrapperwebs wherein the improvement comprises means definingheat-shrunk openings formed in a portion of the liner web of anoutermost closure -flap, and adhesive means bonding the interior surfaceof the outermost closure wrapper to an exterior surface of an adjacentflap through the heat-shrunk openings. f

A further object of this invention is provide a novel multiply bagbottom construction wherein the openings are defined by edges of thermaldegradation, and the material of the inner liner is constructed fromheat-shrinkable synthetic polymeric material.

' A further object of this invention is to provide a novel multiply. bagbottom construction of the type heretofore defined wherein the materialof the inner liner is preferably oriented polymeric material and may be,for example, polyethylene,"

IN THE DRAWING FIG. 1 is a perspective view of a multi-ply bagconstructed in'accordance with this invention, and illustrates thebottom 2 construction thereof prior to folding an outermost closure flapto its final position, as shown in FIG. 4.

FIG. 2 is a fragmentary enlarged elevational view of the bottomconstruction of the bag of FIG. 1, and illustrates the inner surface ofthe outer wrapper of the outermost closure flap exposed throughheat-shrunlt openings of the inner liner.

- FIG. 3 is an enlarged fragmentary sectional view taken generally alongline 3-3 of FIG. 2, and more clearly illustrates the openings of theinnerliner and the manner in which the inner surface of the outerwrapper is exposed therethrough.

FIG. 4 is a fragmentary side elevational view of the bagbottom'construction, and illustrates the outermost closure paneladhesively secured to underlying exterior surfaces of the wrapperthrough the heat-shrunk openings.

A novel multi-ply bag constructed in accordance with this invention isgenerally designated by the reference numeral 10 and includes a bottomconstruction 11 which, insofar as the formation and folding thereof isconcerned, is a conventional square'bottom. Although the invention isdescribed in conjunction with a square bottom bag, it is to beunderstood that satchel or any other conventional bottom constructionmay be employed so long as at least one closure panel is brought intooverlying adhesive contact with another closure panel to form the bagbottom. Furthermore, though the bag 10 will be described hereinafter asbeing formed of only two plies, tubes or webs, it is to be understoodthat the invention can be carried out with any reasonable number ofthicknesses or plies. In addition, though reference is made to an outerwrapper and an inner liner, the invention is likewise applicable tocoatings, as

opposed to webs, of heat-shrinkable material applied to an outerwrapper, or an outer wrapper and an inner liner of which the latter islikewise provided with a coating of heatshrinkable material. The essenceof the invention is the provision 'of any type of multi-ply bag-stockmaterial in which at least one ply, coating, web, or like laminate isconstructed from heat-shrinkable material and is subjected to thermaldegradation to form openings through which an adhesive" bond may beformed to readily cross-bendable material.

The multi-ply bag 10 includes bellows 12, 13 formed by folding alongfold lines 14 through 16 and 18 through 20,

The entire inner surface of the wrapper 21 is covered by the -.liner 22,and the latter may be in the form of a separate web spot pasted orlaminated to the interior surface of the wrapper preferably but notnecessarily oriented polymeric or copolymeric material.

The square bottom 1 l is folded in the manner described more fully inthe latter-noted patent and known in the prior art by first inwardlyfolding a pair of side flaps or closure panels 24, 25, along respectivefold lines 26, 27. An inner closure panel or flap 28 is next foldedalong a fold line 30 into partial overlying relationship to the sidepanels or flaps 24, 25. In

both FIGS. 1 and 2, the exterior surface of the outer wrapper of thepanels or flaps 24, 25, and 28 is exposed.

As best shown in FIGS. 1, 2, and 3, the bag bottom 11 includes anoutermost closure panel or flap 32 formed by the material of both theouter wrapper 21 and the inner liner 22. The stipling in FIG. 2indicates innermost surfaces of the outer wrapper exposed throughopening, generally designated by reference numeral 33, formed in thematerial of the inner liner 22. The openings 33 are formed by subjectingthe liner material to heat sufficient to cause thermal degradationthereof whereupon, due to the heat-shrinkable nature of the inner linermaterial, the openings 33 are formed. Edges 34 of each of the openings33 are irregular, rough, and by visual appearance can be seen to havebeen formed by the thermal v degradation of the material of the liner22.

Prior to folding the outermost closure flap or panel 32 along a foldline 35 to complete the formation of the bag bottom construction 11,adhesive is applied upon the liner 22 of the outer closure flap 32 andthereby contacts the stipled inner surface of the outer wrapper. Whenoverfolded to the position shown in FIG. 4, adhesive thereby bonds theinner surface of the outer-wrapper of the outer closure flap 32 to theexterior surfaces of the flaps or closures 24, 25, and 28. Because ofthe openings 33, it is immaterial that the adhesive upon the impermeableliner 22 in the area of the closu're32 is not ab sorbed thereby becausethe adhesive will be absorbed by the exterior porous surface of theclosure panels, 25, 28, and

the interior surface of the outer wrapper of 'the'closure 32,

thereby achieving an excellent adhesive bond.

While preferred forms and arrangements of parts have been shown inillustrating the invention, it is to be clearly understood that variouschanges in details and arrangement of parts may be made withoutdeparting from the spirit and scope of this disclosure.

lclaim:

1. In a multi-ply bag bottom construction of the type including at leastan inner liner tube and an outer wrapper tube, and

fold line means for defining a flap foldable into exterior 'overlyingrelationship to an adjacent exterior portion of the outer wrapper tube,the improvement comprising means defining heat-shrunk thermal-degradatededges of openings formed in a portion of said inner liner tube at saidflap, and means securing said exterior portion to a portion of saidouter wrapper tube at said flap through said openings.

2. The multi-ply bag bottom construction as defined in claim 1 whereinsaid securing means is an adhesive bond.

3. The multi-ply bag bottom construction as defined in claim 1 whereinsaid inner liner tube is constructed from heatshrinkable syntheticpolymeric material.

4. The multi-ply bag bottom construction as defined in claim 1 whereinsaid inner liner tube is constructed from heatshrinkable syntheticoriented polymeric material such as polyolefin, polyethylene,polypropylene, pliofilm, etc.

- 5. The multi-ply bag bottom construction as defined in claim 2 whereinsaid inner liner tube is constructed from heatshrinkable syntheticpolymeric material.

1. In a multi-ply bag bottom construction of the type including at leastan inner liner tube and an outer wrapper tube, and fold line means fordefining a flap foldable into exterior overlying relationship to anadjacent exterior portion of the outer wrapper tube, the improvementcomprising means defining heat-shrunk thermal-degradated edges ofopenings formed in a portion of said inner liner tube at said flap, andmeans securing said exterior portion to a portion of said outer wrappertube at said flap through said openings.
 2. The multi-ply bag bottomconstruction as defined in claim 1 wherein said securing means is anadhesive bond.
 3. The multi-ply bag bottom construction as defined inclaim 1 wherein said inner liner tube is constructed fromheat-shrinkable synthetic polymeric material.
 4. The multi-ply bagbottom construction as defined in claim 1 wherein said inner liner tubeis constructed from heat-shrinkable synthetic oriented polymericmaterial such as polyolefin, polyethylene, polypropylene, pliofilm, etc.5. The multi-ply bag bottom construction as defined in claim 2 whereinsaid inner liner tube is constructed from heat-shrinkable syntheticpolymeric material.